本文整理汇总了VB.NET中Microsoft.Win32.SafeHandles.SafeFileHandle.SafeFileHandle构造函数的典型用法代码示例。如果您正苦于以下问题：VB.NET SafeFileHandle构造函数的具体用法？VB.NET SafeFileHandle怎么用？VB.NET SafeFileHandle使用的例子？那么恭喜您, 这里精选的构造函数代码示例或许可以为您提供帮助。您也可以进一步了解该构造函数所在类Microsoft.Win32.SafeHandles.SafeFileHandle的用法示例。
在下文中一共展示了SafeFileHandle构造函数的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的VB.NET代码示例。
示例1: SafeHandlesExample
' 导入命名空间
Imports Microsoft.Win32.SafeHandles
Imports System.Runtime.InteropServices
Imports System.ComponentModel
Class SafeHandlesExample
Shared Sub Main()
Try
Dim loader As New UnmanagedFileLoader("example.xml")
Catch e As Exception
Console.WriteLine(e)
End Try
Console.ReadLine()
End Sub
End Class
Class UnmanagedFileLoader
Public Const FILE_ATTRIBUTE_NORMAL As Short = &H80
Public Const INVALID_HANDLE_VALUE As Short = -1
Public Const GENERIC_READ As Long = &H80000000
Public Const GENERIC_WRITE As UInteger = &H40000000
Public Const CREATE_NEW As UInteger = 1
Public Const CREATE_ALWAYS As UInteger = 2
Public Const OPEN_EXISTING As UInteger = 3
' Use interop to call the CreateFile function.
' For more information about CreateFile,
' see the unmanaged MSDN reference library.
<DllImport("kernel32.dll", SetLastError:=True, CharSet:=CharSet.Unicode)> _
Private Shared Function CreateFile(ByVal lpFileName As String, ByVal dwDesiredAccess As System.UInt32, ByVal dwShareMode As System.UInt32, ByVal lpSecurityAttributes As IntPtr, ByVal dwCreationDisposition As System.UInt32, ByVal dwFlagsAndAttributes As System.UInt32, ByVal hTemplateFile As IntPtr) As IntPtr
End Function
Private handleValue As SafeFileHandle = Nothing
Public Sub New(ByVal Path As String)
Load(Path)
End Sub
Public Sub Load(ByVal Path As String)
If Path Is Nothing AndAlso Path.Length = 0 Then
Throw New ArgumentNullException("Path")
End If
' Try to open the file.
Dim ptr As IntPtr = CreateFile(Path, GENERIC_WRITE, 0, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero)
handleValue = New SafeFileHandle(ptr, True)
' If the handle is invalid,
' get the last Win32 error
' and throw a Win32Exception.
If handleValue.IsInvalid Then
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error())
End If
End Sub
Public ReadOnly Property Handle() As SafeFileHandle
Get
' If the handle is valid,
' return it.
If Not handleValue.IsInvalid Then
Return handleValue
Else
Return Nothing
End If
End Get
End Property
End Class